Numerical Simulation Of Sediment Movement And Its Dynamic Mechanism In A Strong Wind Processes Of Northern Sea Of The Yellow River Delta

Strong wind above6level always happens in the northern sea of the Yellow RiverDelta, water level rise caused by the superposition of storm surge and astronomicaltide during the windy periods, making coastal erosion, wharf breakwater collapse andother accidents occur easily with the huge storms, lead to huge economic losses. Inextreme sea conditions, sediment movement hyperactive, lead to sediment disasters:oil platforms, pipelines destroyed and waterways basin sedimentation. So the studiesof sediment movement and its dynamic mechanism under extreme sea conditions arevery important. This paper systematically analyzes the impact of wind in stormsurges, waves, erosion and deposition etc, have a practical significance for disasterearly warning and protection of coastal engineering during the strong wind.In this paper, a storm surge model and wave models across the Bohai Sea wasestablished and wind data measured in the center II platform as input conditions. Thispaper analysis the impact of wind on hydrodynamic combined with the measuredwind, tide, currents, wave data.The result shows that:①N,E wind can cause waterincrease and S,W can cause water reduction in Northern Sea of the Yellow RiverDelta;when the direction of wind and flow are same,the current velocity increase,andvice versa; E, NE wind can produce large waves in study area because of longer fetchlength.②Under the influence of the SW wind, water reduction occurr in study area,the value is about0.3m; dramatic level increase in this area on the impact of E wind,water increased value is above0.8m; the contour line north-south distribution, waterincreased value is greater in west than that in east; under the E wind, the studyarea become ebb dominant; whether E, NE or W, NW wind, waves become smallerfrom the east to the west gradually, the wave contour line approximately parallel tothe isobaths, but E,NE wind lead to larger wave.This paper analyzed the correlation between suspended sediment and wave,current, calculated the suspended sediment distribution, erosion and deposition of Bohai Bay and Laizhou Bay, the results show that:①Temporal distribution ofsuspended sediment concentration is mainly affected by the wave height, the spatialdistribution of suspended sediment is controlled by tide and waves, the position ofhigh value center of suspended sediment under waves and currents is similar with thatunder tidal current only,but the value improved greatly.②In2013April theeast wind occurs frequently, the actual erosion was impacted by wave,the erosion ofQingshuigou estuary has a greater degree improvement,and the northern sea of theYellow River Delta also changed:firstly the erosion amount of offshore erosion centernear5m isobath is above2cm per month, secondly erosion occurs inshore in thesouth of offshore erosion center.Sediment grain size characteristics measured before and after a gale showed that:gale significantly reduces the particle size of the5th-8th stations between1.5m-4misobath. This phenomenon is caused by the E wind and the flow field characteristicsof study zone: E wind lead to coastal sediment movement and the reduce of currentleads to the settlement of silt sediment,causing sediment fining.